Optical devices such as homogenizers typically receive one or more optical beams at an input, even out the irradiance (power/unit area) profiles of the light, and produce a single uniform optical beam at the output. In many optical testing and inspection applications a range of optical beam size outputs is desired or the required output beam size is not known a priori. However, the outputs of existing optical devices are fixed in size.
Currently, there are essentially two solutions to the problem of producing variable sized output beams from an optical device having a fixed output size. The first approach is to create a multitude of optical devices each having a specific fixed output size. Unfortunately, this approach is, among other things, time consuming, inefficient, and expensive as a new optical device must be built for every desired optical beam output size.
In the second approach, the output size of the optical device remains constant while the optical beam is resized using an aperture of an appropriate size to control beam size by clipping the edge of the beam at the output of the optical device; i.e., the aperture removes any light from the beam outside the desired beam size. However, in this approach, while the irradiance value (power per unit area) remains constant, the total power of the beam is decreased.
Furthermore, as the aperture can only reduce the beam size, the second approach does not lend itself if an increase in beam size is desired. If it is anticipated that a large beam might be needed at some point, then the optical device must be configured to accommodate the largest anticipated beam size. The irradiance in this large beam then becomes the maximum irradiance available for all smaller beam sizes. If higher irradiance values are desired for the smaller output beams, then, as indicated previously, a new optical device would need to be built.
Accordingly, there exists a need for a variable sized optical apparatus and method thereof for receiving one or more optical beams and for producing different sized substantially uniform beam outputs.